The broad objectives of this K08 proposal are two-fold: 1) to foster the development of essential scientific and professional skills that will allow he candidate, Dr. Benjamin Singer, to achieve his long-term goal of becoming an independent physician-scientist concentrating on epigenetic modifications as therapeutic targets in lung pathology, and 2) to investigate mechanisms that direct the immune system to resolve a severe lung disease. Through laboratory experience, coursework in the Bloomberg School of Public Health, and the peer review process, Dr. Singer will gain expertise in experimental design, laboratory procedures, data analysis, and scientific communication. Dr. Singer and his mentors at Johns Hopkins University, Drs. Srinivasan Yegnasubramanian and Franco D'Alessio, have designed a specific training plan that will afford Dr. Singer new knowledge and research skills in the pathobiology of acute lung inflammation and acute respiratory distress syndrome (ARDS), which is a lung condition that causes tremendous morbidity and mortality in the United States. Despite extensive research into the initial injury and inflammation that drive ARDS, no targeted therapies accelerate its resolution. Experimental studies established that committed regulatory T cells (Tregs)-immune system cells that limit inflammation and orchestrate repair of damaged tissues-resolve inflammation in mouse models of lung injury. However, the mechanisms that cause Tregs to execute their pro-repair program following lung injury remain unknown. Our preliminary data identify DNA methylation, which involves a DNA methyltransferase adapter protein known as Uhrf1, as a critical phenomenon limiting expression of the main protein that directs Treg pro- repair function: Foxp3. Thus, we hypothesize that Uhrf1 deficiency in committed Tregs will lead to Foxp3 locus hypomethylation, increased Foxp3 expression, and enhanced Treg pro-repair function that facilitates resolution of acute lung injury. To test this hypothesis we propose the following Specific Aims: 1) define the role of Uhrf1 in promoting DNA methylation at the Foxp3 locus in committed Tregs following lung injury, and 2) define the role of Uhrf1 on committed Treg pro-repair function and immunoregulatory phenotype. To specifically test our hypothesis we are breeding novel mice that have Uhrf1 deficiency only within Tregs. We have also designed an RNA interference strategy to acutely knock down Uhrf1 in cultured Tregs. Major methods for this proposal include an established mouse model of acute lung injury (intratracheal lipopolysaccharide administration), DNA methylation sequencing techniques, and multicolor flow cytometry. Accomplishment of these aims will provide a rigorous training program for Dr. Singer and uncover mechanisms controlling Treg function during resolution of acute lung injury that could be translated for therapeutic benefit in ARDS.